Since 1980, the population of U.S. federal prisons has climbed nearly eightfold. A recent report by the Congressionally-created Task Force on Federal Corrections attributes most of the growth in federal prison populations to two factors, both related to drug-crime sentencing.

First, drug offenders make up the lion’s share of those in federal prisons. At the end of fiscal year 2013, the most recent period for which data are available, more federal prisoners had been incarcerated on drug charges than on all other types of federal crimes combined. Federal prisons held roughly 50,000 more convicts on drug charges than was the case two decades earlier.

Second, even though the number of new prisoners entering federal prisons each year on drug charges has remained level at about 30,000, drug offenders now make up a greater share of the overall prison population, since they draw longer sentences and are less likely to be released early.

Sentences for prisoners convicted on federal drug charges include imprisonment in about 95% of all cases, compared with the roughly 76% of drug offenders who drew prison terms several decades ago. That’s largely because of the Anti-Drug Abuse Act of 1986, which mandates minimum sentences for many drug offenses, including drug trafficking, which is cited in 95% of federal drug prosecutions and included in the sentences of about 60% of drug prisoners.

Its mandatory minimum sentence can range from a year to life, depending on the particular charge. The average sentence for drug offenders being held at the end of fiscal year 2013 was about 11 years. Of recent prisoners, nearly none were released before serving at least 87% of their sentence.

While about a quarter of prisoners sentenced for drugs also had weapons charges, about a third had little or no previous criminal history when they were sentenced. The report also noted the disproportionate effect of drug sentences on some minority groups. Of federal drug-offense prisoners in the most recent year for which figures are available, more than three-quarters were black or Hispanic.

The Task Force is far from the only group calling attention to what it sees as the need for smaller prison populations and revised sentencing. A new coalition, comprised of an unlikely combination of liberal and conservative groups, also plans to focus on reducing the prison population, by revising sentencing rules and finding ways to cut repeat offending. The Coalition for Public Safety, announced in February, includes such odd bedfellows as conservative stalwarts Koch Industries, FreedomWorks, and Americans for Tax Reform, alongside liberal groups such as the American Civil Liberties Union, the Center for American Progress and the Leadership Conference Education Fund.

A statement for the new group says it will “work across the political spectrum” to recommend and build consensus for comprehensive reforms in local, state and federal criminal justice systems. Its announced goals include:

reducing the numbers, and associated costs, of jail and prison inmates